VDEP, or Vegetation Departure is an ecosystem condition metric that compares modeled historical amounts (reference) of ecosystem succession classes (a.k.a. “seral states” or “developmental classes”) to current. The final output is a single number per ecosystem that ranges from 0 to 100. When you download VDEP data from LANDFIRE (https://www.landfire.gov/vdep.php), this is what you get-that final number (VDEP math is pretty simple as in example table below for one imaginary unnamed ecosystem. VDEP is 48 in the example).
When you map the VDEP data, you are essentially mapping 0 to 100 for all ecosystems within the area of interest such in this map of VDEP for the coterminous United States.
While interesting and useful for general assessments, the downloaded VDEP data does not tell you which succession classes are over or under represented-you only get the 48 in the example table above. To get at over and under representation we need to get the amounts of each succession class for the Biophysical Settings (ecosystems) that occur within our area of interest.
The figure below (from Swaty et al., 2011) illustrates this point. In the three examples below we worked up data that separates out the amounts of succession classes allowing the reader to see where management work might need to happen (we do not provide prescriptions for what should be done-that is for local managers and stakeholders to do).
Departure from reference conditions can be caused by (A) increases in uncharacteristic vegetation, as in Great Basin Salt Desert Scrub, (B) increases in closed canopy successional classes, as in Ozark Oak Woodland, or (C) increases in early successional classes, as in Cascades Western Hemlock Forest. These vegetation changes are the expected outcomes of biological invasion, fire suppression, and logging, respectively.
We need reference and current amounts of each succession class for each ecosystem. Where do those come from? From www.landfire.gov . 😄
For our work here we will use the refCon200.csv (path to file is “rawData/refCon200.csv”) file to get reference conditions.
For our work here we will use the combine200s.csv (path to file is “rawData/combine200s”) dataset.
BTW: what is all of this “200” business? It refers to the most recent LANDFIRE dataset.
In general data prep, then visualization. More specifically:
This dataset is not “Tidy”. What does Tidy mean? It means that a dataset follows these 3 rules:
You need to figure out what is going on with the reference data and fix it. Here’s what you need to do: